Vapor discharge device



Nam 17, @3315 T. E. FOULKE VAPOR DISCHARGE DEVICE Filed March 2, 1.925

"Hus ATTORN Patented Nov. 17, 1931 omen STATES PATENT OFFICE] TED E. FOULKE,,0F NUTLEY, NEW JERSEY, ASSIGNOR TO GENERAL ELECTRIC VAPOR LAMP COMPANY, OF HOBOKEN', NEW JERSEY, A. CORPORATION OF NEW JERSEY' VAPOR DISCHARGE DEVICE The present invention relates to vapor discharge lamps of the electrode type. The invention relates more particularly to electrodes for such devices and the forms of such electrodes, to the in-leads for the electrodes, to method and means for protecting the seals for the leads, to the particular atmospheres provided in the devices, and to other relations of various parts to one another.

The invention further relates to vapor discharge devices which have a complementary gas or vapor therein to aid in the transfer of electrical energy from a source to a radiation sustaining or emitting gas of vapor.

Various objects and advantages of the invention will be apparent from the specification and claims from the accompanying drawings.

In vapor discharge devices such as positive column, negative glow, and vapor arc lamps, vapor or gaseous rectifiers, in electronic valve devices and the like radiations are produced or sustained in a gas or vapor by energy applied thereto through electrodes terminating therein or by induction. In devices of this kind in which electrodes are used for applying the energy sputtering of the electrodes is caused by bombardment of the material thereof principally by positive ions of the gas or vapor of the devices. I have found however that the rate of sputtering is directly proportional both to the atomic weight of the gas or vapor and to the atomic weight of the metal or material of the electrode. Further to reduce the amount of sputtering to a minimum I make the electrodes of metal or material of low atomic weight and use a gas or vapor of low atomic certain gases which are most suitable for the efficient transformation of the energy are also of very low atomic Weights and therefore most desirable from the standpointof a small degree of electrode sputtering when 'used in devices of this kind. Also those gases mostdesirable on account of the color or quantity of radiations therefrom are not those having the lowest atomic weights.

But I findthat certain ases which are desirable on account of the ind and nature of highly eflicient as an energy transmitter and another is highly efficient as an illuminant. In such a mixture the transmitter serves to pass energy from the source to the illumination orradiation supporting gas. In such an action the atoms or molecules of the ener transmitting gas pass energy on to atoms or molecules of the radiation producing gas during collisions therewith. Such collisions are known in physics as collisions of the second order. s

Accordingly in devices of this kind I use a mixture of certain gases comprising two components, one a-radiation supporting component and a component for transferring energyfrom the source to the radiation supporting component. For the radiation supporting component I use a desired gas or vapor in comparatively small quantities and use the energy large quantities.

Further I find that the energy transferring component can be chosen as a gas or vapor having a very low atomic weight, heliumhaving a very low atomic weight and being very efficient in transferring energy to another gas or vapor. For the radiation supporting medium a gas is chosen with as low an atomic weight as possible, neon being suittransforming component in ally not more than 5% of neon that illumis 1 nation can be; very ieflicicntly produced In: a negativeglow lamp,

-Argon is used with the helium 111501118 cases to assist in energy transmission: as its low ionizing potential is of material; assist. I

I ance :in starting the device into operation,

I but usually in quantities not over 5% on ac- I -count of its comparatively high: atomic weight. Hydrogen is; in some cases used in the lamp-is quickly reduced to such a: low rate of efficiency. as to be unsuitable. for use, In: the case of lead glass this rate: of tdepreci-a-I tion- .is particularly high. on account of the I 'highatomio weight of the metal lead, the rate I I I small quantities to keep the: surfaces I of the electrodescleam I I I invention to and the embodiment thereof-in I lamps of the negative glow type but it. is to; l

I be understood that: various parts thereof are also applicable to otherlampssuclras vapor I are lamps and positive column lamps, and: to oth'erelectricaldevices; i I i I i i I I p 5 electrode material, of temperature: at :difi'er-.

I ten-ting means for theseal-ins and fortheleads I In negative glow lamps non-uniformity I ent points on the discharge surface of the I electrode, and of other conditions and charac-i 'teristics produce :or cause darkspots on the- :electrode or areas at which no glowdischarge is produced. To preclude. the 1 occurrence :of suc'h dark spots and'to overcome-the effect of I ltli'emI' provide an electrodeihaving a multi-. i .plicity of comparatively closely spaced-points: :or projections or extended ridges which act as discharge points and aspointsof high curs rent density whereby there is insured the production of radiation at a multiplicity of points uniformly distributed over a discharge area. In cases and under conditions where some areas would be dark this uniform distribution of light through the multiplicity of points will overcome the effect of the dark spots. In other cases discharges will be started 11 in the dark spots by the production of ra iation at points within the dark areas. In any case a uniform and desirable lighting effect will be produced.

In discharge devices of the sealed-in electrode type difficulty is experienced and the life of the device is impaired by deterioration of the seal from the action of positive ions and electrons which are produced by the discharge and which upon contact therewith attack and break up the materials of the seal. To overcome the action of the positive ions and also of the electrons I provide at the seal a coating of material which will prevent the positive ions and electrons from reaching the materials of the seal.

In discharge devices of the sealed-in electrode type difliculty is experienced due to the disintegration of the glass at the seal-in through bombardment thereof by positive ions from the electrodes and from the elec- 1 In the specification andzthe drawings there i I isshown and described the appllcation of my;

trode leads. I This. bombardment is particu-- larly destructive when. the seal-ins of bothelectrodes are closetogcther or at a cnlnmon. I I

seal: dueto the strong electrostatic field between 1 the I leads and: between I the electrodes which the positive ions possess when they strike thematerialof the seal-ins: The-glass Z of. the seal in is disintegrated by the positivewas when they. strike it and the: metal. of the glass upon I being freed: is sputtered throughout the lamp and onto the wa llthcre :ofwhererit causes blackening.- "lhis sput I tering: takes place at such a: high rate that of sputtering beingproportional, I have dis i covered, tothciatomic Weight. I have furs very low: rate and that I such: metals or com- I pounds thereofserve as highly efficientprm by 100% and moreby the; use of; such protcc;

of compoundsof light metals such as caesium cium oxide, aluminum oxide or carbonates of these metals, and so on. These metals, aluminum, lithium, magnesium, calcium and so on are also applicable as paints to the surfaces to be protected. Lithium and lithium oxide I find are very highly desirable for this use on account of the low atomic weight and the high boiling point of the metal. The lithium oxide is applied, for example, by making a paste thereof with distilled water, forming a coating on the parts to be protected and drying the water therefrom.

The electrode material itself is of course subject to the sputtering action in a manner similar to that of the material of the sealins and of the leads, and these also may have the amount or rate of sputtering therefrom decreased by forming a coating thereon of metal of low atomic weight or of a compound thereof, or the electrode itself is made of a low atomic Weight metal or alloy. This coating may be applied by electro-pla-ting, dipping, painting or any other well known means. I

I find, however, that this coating may be derived from a material used as a protective coating at the seal-ins, the coating of protective material being sputtered thereonto by bombardment of the protective coating on the thereatand that the length of-lifeozf the de. vice in which they are-used may be increased I tive; materials Materials which I :I; have I foundprcferable for such protecting means.

aresleeves oflithiuimaluminum,magnesium, I i I andother light Weight metals,and'coatings oxide, lithium oxide, magncsiumoxide, calseal-ins by positive ions during preliminary or initial use of the lam or device. The coating may also be applie by heating the oxide in a partial vacuum. I find it imperative,

however, to provide the seal-ins with the protective coating prior to any use of the lamp or device because of the comparatively heavy atomic weight of the metal of the'glass and the attendant rapid deterioration thereof and blackening of the lamp when the protective coating is absent from the seal-ins, the rate of blackening being so rapid that the device is rendered unsuitable for use before a protective coating can be formed at the seal-ins be- In negative glow lamps it is usually found necessary to employ resistances in series with a lamp for stabilizing a current flow in order that advantageous pressures of gases may be employed in accordance with laws well known in the art. -In one form of device embodying this invention a part of the glass of the envelope is used as the stabilizing resistance,

the lead to an electrode being terminated at a short distance from the electrode and glass being fused thereover to serve as a resistor between the end of the lead and the electrode terminal.

In the accompanying drawings is shown 6 for purposes of illustration one form of mechanism with certain modifications thereof embodying the invention, in which Fig. 1 is an elevation view of a glow lamp having circular electrodes in which are turned grooves and ridges to produce a multiplicity of points extended uniformly over the discharge areasof the electrodes.

Fig. 2 is a face elevation view of a flat electrode which is scored at a multiplicity of lines to produce points extended uniformly over the discharge area of the electrode.

Fig. 3 is an elevation view of a fiat electrode showing a face scored to provide projecting points,

4 Fig. 4 is an elevation view of a lamp similar to that of Fig. 1 but with flat scored electrodes such as is shown in Fig. 3,

Fig. 5 is a vertical elevation view in part section of an electrode seal-in part of a lamp 50 or the like showing electrodes formed over the glass of the seal-in and with protective material on the seal-in between the electrodes, and

Fig. 6 is a vertical section view in elevation of a glass seal-in stem with an electrode lead having an end sealed'into said stem and terminating therein, an electrode in the form of a cap mounted on said stem and protective material below the electrode.

Referring to Figs. 1 and 2 of the drawings the envelope 1 having a screw base 2 has mounted thereinthe electrodes 3 connecting with said base 2 by the leads 4 in the conventional manner. On said electrodes 3 which are circular in cross section are formed fore such a degree of deterioration occurs.

thespiral ridges 6which present a plurality of projecting points extending uniformly over the discharge area of the electrodes. At the points of seal-in of said leads 4 through their supporting stems 7 and over the leads and stems 6 at and near these points is provideda covering of protective material 8 of lithium oxide, calcium oxide, magnesium oxide, aluminum oxide, or sleeves or paint of metal of these compounds or the like.

Referring to Figs. 3 and 4 the glow electrodes 3', 3 are in the form of flat sheets mounted parallel to each other on the leads 4, 4 and are formed with scorings therein or grooves'to provide the raised points 6'. The leads 4, 4 and the seal-in stems 7, 7 have coatings of protective material 8, 8 thereon and on leads 4, 4, between 'patings 8 and the electrodes 3' is mounte'di' t baflie plate 10 which is formed of lithiuni' oxide, calcium oxide, aluminum oxide or the like or of material such as mica, for example, having-a coating of protective material thereon.

In Fig. 5 the stem 14 carries the seal-in stems 15, 15 through which are sealed the electrode leads 16, 16 which terminate at a short distance above the upper end of the respective stems 15,15. Mounted about stems 15, 15 and making electrical contact at the upper ends of said lead-ins 16, 16 are the electrodes 18, 18 which are in the form of caps. Below said electrodes 18 on stems 15 and on' gtem 14 is the covering of protective material In Fig. 6 the stem 21 has sealed thereinto and terminating therein the electrode lead 22. About the upper end of stem 21 is mounted the electrode 24 which is in the form of a cap fitted closely to the stem.- The glass of the stem about the end of lead 22 serves as a stabilizing or ballasting resistance for the circuit to which said electrode 24 may be connected, a-glass suitable in this use is one containing an appreciable amount of lead or aluminum, such for example as a lead or an aluminum borosilicate' glass. Below said elec trode 24 and for an appreciable distance there is provided the covering 25 of the protective material above described.

It is to be understood that the practice and application of my invention is not limited to the use of the metals above described and the compounds thereof because as will beapparent varying degrees of eiiiciency over the non-protected devices can be obtained by selecting the protecting materials which are less responsive to the sputtering effect of the positive ions than is the material to be protected.

I have made negative glow. lamps having a filling of helium about 95% and neon about 5% and having magnesium electrodes and with a metal oxide of low atomic weight as a protective covering between the electrodes which will start and operate at voltages as low as volts direct current, and 50 volts alternating current. These protective materials, it is to be understood, are not limited to use with the double component gas or vapor filling but function in the same manner in lamps having but one gas or vapor such as mercury, helium, or any other.

In the claims the phrase on the inside ofthe envelope wall at and near the seal-inpoint or avariation thereof has been used to cover the stem commonly used in such devices, or the area adjacent to the electrodes at the seal regardless of construction.

I claim 1. In an electric vapor discharge device having electrodes sealed into an envelope, a protective coating of a material having alow atomic Weight inside of the envelope on the electrode lead-ins at and near the seal-in point.

2. In an electric vapor discharge device having electrodes sealed into an envelope, a protective coating of lithium oxide inside of the envelope on the electrode lead-in at and near the seal-in point.

3. In an electric vapor discharge device having electrodes sealed into an envelope, a protective coating of an alkali oxide having a low atomic Weight on the electrode lead-in at and near the seal-in point.

4. In a vapor discharge electric device, comprising a sealed envelope having electrodes sealed thereinto, a covering for parts at and adjacent to the seal-ins of material comprising a metal of low atomic Weight.

5. In a vapor discharge electric device, comprising a sealed envelope having electrodes sealed thereinto, a covering for parts at and adjacent to the seal-ins of material comprising a metal of low atomic Weight in the oxidized state.

6. In a vapor discharge electric device, comprising a sealed envelope having electrodes sealed thereinto, a covering for parts at and adjacent to the seal-ins of material comprising a metal of low atomic Weight and having a high boiling point.

7. In a vapor discharge electric device comprising a sealed envelope having electrodes sealed thereinto, a covering for parts at and adjacent to the seal-ins of material comprising lithium.

8. In a vapor discharge electric device comprising a sealed envelope having electrodes sealed thereinto, a covering for parts at and adjacent to the seal-ins of material comprising lithium in the oxidized state.

9. In a vapor discharge electric device comprising a sealed envelope having elec trodes sealed thereinto, a covering for parts at and adjacent to the seal-ins of material comprising a metal of low atomic Weight lower than that of metal in the glass at said seal-ins.-

10. In a vapor discharge electric device, 2.

sea-led vitreous envelope, electrodes formed on the inner surface of said envelope, and leads sealed through the envelope wall to said electrodes, and a protective coating on said envelope Wall between said electrodes.

11.. In a vapor discharge electric device, a

' sealed vitreous envelope, electrodes in said envelope, and electrode leads terminating Within a short distance of respective electrodes, portions of the Wall or" said envelope servingas resistances between the electrodes and their respective leads. a

13. In a vapor discharge electric device, a sealed vitreous envelope, electrodes in said envelope, and electrode leads terminating within a short distance of respective electrodes. portions of the wall of said envelope serving as resistances between the electrodes and their respective leads and a protective coating on the inner Wall of the envelope between said electrodes. I

Signed at Hoboken, in the county of Hudson and State of New Jersey, this 19th day of February, A. D. 1926.

. TED E. FOULKE. 

